Analysis and modelling of reactive three-dimensional high-power CO 2 laser cutting

Abstract

A model of the process of cutting metal with a gas assisted CO₂ laser beam has been derived with the principal objective of understanding the role of manufacturing parameters both from its kinetics and its chemistry. The model considers the cutting front as a surface phenomenon for reaction and absorption. An adjusting parameter, m, is introduced in this model to represent the absorptivity for different materials and different incident angles. The mass diffusion rate at the gas/solid boundary of the cutting front is included in this model to investigate the exothermic heat which will be released at the cutting front during the cutting process. The effects of oxide films, polarization, cut front shape, cutting speed and laser power have been analysed. The tendency of the experimental results from many previous researchers agrees with the prediction of these theoretical results. It is shown that very small levels of impurity in the oxygen would be expected to have a significant effect on the cutting performance.

Keywords

gas assisted high power cutting

References

Steen

W. M.

Kamalu

Laser cutting. In Laser Materials Processing (Ed. Bass

), 1983, Ch. 2 (North-Holland Publishing Co., New York).

Ivarson

The role of oxidation in laser cutting stainless and mild steel. J. Laser Applic., 1990, 3(3), 41–50.

Matsunawa

Interaction between supersonic jet and burning iron wall in oxygen gas cutting (Part 1). Trans. JWRI, 1985, 14(1), 45–54.

Yilbas

B. S.

Sahin

A. Z.

Oxygen assisted laser cutting mechanismâ a laminar boundary layer approach including the combustion process. Optics and Laser Technol., 1995, 27(3), 175–184.

Olsen

F. O.

Investigation in optimising the laser cutting process. In ASM Conference on Applications of Lasers in Materials Processing, Los Angeles, California, 24–26 January 1984.

Steen

W. M.

Laser Material Processing, 1991 (Springer-Verlag Limited, London).

Eckert

E. R. G. S.

Draka

R. M.

Analysis of Heat and Mass Transfer, 1972 (McGraw-Hill Inc., New York).

Arata

Dynamic behaviour in laser gas cutting of mild steel. Trans. JWRI, 1979, 8(2), 175–186.

Powell

Ivarson

Kamalu

Broden

Magnusson

The role of oxygen purity in laser cutting of mild steel. In ICALEO, Orlando, Florida, 1992, SPIE Vol. 1990, pp. 433–442.

10.

Holman

J. P.

Heat Transfer, 7th edition, 1990 (McGraw-Hill Inc., New York).

11.

Wells

A. A.

Oxygen cutting. Br. Weld. J., 1961, 86–92.

12.

Wells

A. A.

Further studies of iron-oxygen combustion in gas cutting. Br. Weld. J., 1991, 79–85.

13.

Benedict

R. P.

Fundamentals of Pipe Flow, 1980 (John Wiley, New York).

14.

Gabzdyl

J. T.

The effect of oxygen purity on laser cutting of steels. Report COE/JTG/001. BOC Limited, UK, 1991.